Block-signal system.



, L. A. HAWKINS BLOCK SIGNAL SYSTEM. APPLICATION FILED MAR.18,1 90.

93 73 -139. Patented Oct. 19,1909. E v w o I? l v I J;

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JNYEH'TU .Zlavazwcs A. HAWKZNS.

UNITED sTA'rEs PATENT OFFICE.

LAURENCE A. HAiIVKINS, or SCEENECTADY, NEW Your; assronoa 'ro GENERAL ELECTRIC COMPANY, A CORPORATION or NEW YORK.

BLOCK-SIGNAL SYSTEM.

Specification of Letters Patent.

Patented Oct. 19, 1909.

Application filed; March 18, 1909. Serial No. 484,230.

To all whom it may concern."

Be it known that I, LAURENCE A. HAw-' KIXS, a citizen of the'United States, residing at Schenectady, in the county of Schenec tady, State of New York, have invented certain new and useful Improvements in Block- S1gnal Systems, of which the following. is a specification.

My invention relates to alternating current block signal systems-for electric roads, and its object is to provide a novel arrangement of track circuits, wherebya single.

trackrcireuitmay suffice for controlling successively a plurality of difl'erent signal operations as the car reaches difierent points on the track circuit. Y

It has been customary heretofore to efnploy at least one track circuit for each si 'nal operation,-that is, the track circuit not extend farther than from one si alto the next. In passing through inter ocking or through crossovers and sidings, the signals may be very close together, and the track circuits exceedingly short. In ,an alternating current signal system, the multiplication of track circuits is highly objectionable. For instance, if the system is of the type in which inductive bonds, are used for conveying the power current from one block to another; additional track circuits mean additional inductive bonds, which may be exceedingly expensive. Furthermore, in any system additional transformers are required for additional track circuits, which not only increase the cost of the apparatus, but also increase the current consumption.

By my invention the necessary number of track circuits is greatly diminished, since it renders it unnecessary to start a new track circuit at each signal. track circuit may be given the proper length for most efficient operation, without re ard to the number of signal operations which must be successively controlled by a car in passing over that distance.

My invention consists in the addition to the usualclosed track circuit of a relay or relays connected to the rails, and preferably in shunt to a portion of the track circuit, at any oint or points where thepassage of a car s ould initiate an additional signal movement.

.My invention is applicable to the operation of signals guarding cross-overs and sid- In most cases the' ings in the middle of a block, and also to signal-track operation where it is desirable that the signals for controlling the traffic in opposite directions should be staggered with respect to each other, inorder to provide the volves two track circuits between adjacent signals for the same direction of traflic. By my invention the My invention will best be understood by reference to theaccompanying drawing,

which shows diagrammatically one type of signal system fora signal-track road arranged in accordance with my invention.

lInthe drawing A represents the track rails, both of which are indicated as conductively continuous for all currents throughout their length,-that is, bonded in the manner usual on electric railways. I have illustrated my invention applied to a system adapted for use on such a railway and having its track circuits not separated by insulated joints, but I wish it understood that in its broader aspects my invention is equally applicable to systems of the inductive bond type. Furthermore, when applied to an electric road with the rails conductively continuous, my invention is not limited to the particular type of system which I have selected for purposes of illustration, which type of system is that described in my prior application, Serial No. 435,861, filed June 1, 1908.

1 rent for the signal circuits is taken.

0 and C represent transformers for supplying alternating current to the track circuits. Their. primaries are connected to the transmission wires b, and their secondaries connected across the rails through a resistance or impedance 0, which serves to limit the current drawn from the transformer when a car stands across its terminals, and also prevents saturation of the transformer by unbalanced ower current.

D, D and 3 re resent conductors connected across the rai s at points between ad- Irum'ber of track circuits may be cut in ha-1;.

jac ent trahs'forinefs. In the particular systom shown these conductors form with the transformers and. the track rails closed track circuits, each conductor and each transformer being common to two adjacent track circuits.

E to E represent track relays havmg their track windings connected in shunt to short lengths of rail adjacent to the crossconnectin conductors, These relays are illustrate diagrarmnatically as of the twophase induction type, comprising a shortcircuited secondary member 6 carrymg the relay contacts, a track winding 6 and a second winding e supplied with current directly from the transmission wires through the transformers F F etc. Phase controlling devices, such as condensers a employed, if necessary, to produce the proper phase displacement between the currents in the windings e and 0 The points on the rails, to which each of the conductors D D etc., is connected are not exactly opposite, but are somewhat displaced, so thatadjacent track circuits slightly overlap to insure the shunting of the relay on one side of the con ductors before the relay on the other side of the conductor is energized. The arrangement of track circuits, as far as described, is

identical with that disclosed in my earlier application, above referred to.

lays are preferably provided with two track In addition to the track relays alreadymentioned, track relays E and E are provided at intermediate points on the track cir cuits. The exact location of these relays will be determined by operating conditions. They are indicated as not very far distant from the transformers C and G These rewindings e}, which are connected in shunt to opposite short lengths of rail. While the two windings are not essential, they are advantageous, since by their use the length of rail spanned by a single winding may be cut in half, and furthermore, such power current as flows through the two windings produces opposite magnetizing efi'ects inthe two coils,

so that the tendency to saturation is reduced.

G, G and G represent line relays controlled by the track relays in the manner which will be ex la'ined. 7

H, H and 8 represent signals for controlling traffic in one direction, and H and H represent signals for tratlic in the o posite direction. The signals H, H an H are placed at the ends of the track circuits,- that is, near the cross-connecting conductors D, D and-D The signals H and H are placed atthe track relays E and E". It is the location of these signals which determinesthe position of the track relays. Ordinarily it is desirable that the signal H, for instance, should be ut approximately midway between signal H and H and this brings the relay E not far from the transinay be cameo former C, if that transformer is placed about half way between signals H and H",- as is ordinarily preferable. If a greater overlap is desired, the relay E and signal H would be moved farther away from the transformer C, so as to introduce a greater distance between signals H and H.

It will be seen that the operating circuit of signal H extends through the upper contact of line relay G lower'contact of line relay G secondary of transformer F and through the common return'wireJ to signal -H Line relay G is controlle by track relay E and track relay E,its circuit passing through the contacts of these two relays in series, and then through the secondary of transformer F? and common return wire Similarly, line relay G is controlled by track relays E and E Since a car between conductors D and D will denerg'ize one of the two relays and E and a car between conductors D and D will den ergize one of the two' relays E and E, it follows that a car at an point between conductors D and D will c energize one of the line relays G and G and therefore will hold the signal H at stop. The operating circuit of signal H extends through relay E", relay E lower contact of line relay G secondary of transformer F and common return wire f, back to the signal mechanism. A car between conductor 1) and relay E, while holding signal H at danger, will have no effect on signal H. As soon as it passes relay E, however, it shunts this relay and puts signal H at stop. It will hold this signal at stop until it; passes conductor D, since while it is between transformer C and conductor D relay E is denergized, and while it is between conductors I) and D relay E or relay E is deenergized, and consequently line relay 3 will be deenergized. The zone of control for the signals controlling traffic from right to left is thus a distance twice in length the distance between transformers, while the zone of control for signals controlling the trafiic from left to right is only a little over one and a half times the distance between adjacent transformers. The number of track circuits is. only half that ordinarily'emplo ed for controlling such an arrangement o signals, as is shown, while the same signal operations with regard to overlap are obtained as with the usual numben of track circuits.

It will be noted that the addition of the if other signal operations are required between con uctor D and the transformer 3C as many additional relays may be shunted memo across short portions Of rail at the necessary points as there are signal operations required. The applicability of -my invention to various conditions arising at QISQSSl-QVQIS,

Z sidings, etc., will be vobvious ito-those skilled in the art. Accordingly, I do not desire to limit myself to the particular connections and arrangements .ofparts have shown, but,

aim in the ap ended claims to cover all modifications wlthin the scope'of my invention. H i

What I claim as new and desire to secure by Letters Patent of the United State s,is'-

- and havin a windi 1. In a block signal system comprising signals for the blocks with control circuits therefor, a source of alternating current connected across the track, a track relayat a distance from the source supplied with current therefrom through the track rails, and

a second track relay located at a point intermediate the source and the first track relay and having a winding energized by the current flow past that the first relay.

2. In a block nected across the track, a track relay at "a distance from the source supplied with-current therefrom through the track'rails, and

a second track relay located at a point'intermediate the source and ,the first track relay 1 energized by the-eura point herentflow in both ra1ls past that tween the source and the first rela 3. In a block signal system comprising signals for the blocks with control circuits therefor, a source of alternatingcurrent connected across the track, a track relay'at a distance from the source supplied w1th ,cur-j rent therefrom through the track rails, and

a second track relay shunt to a; short length of the track circuit at a point intermediate the source and the first relay, the contacts of thetwo relays being connected in diiferent'cont'rol circuits; I a 4. In a block signal system comprising signalsfor the blocks with control circuits therefor, a source of alternating current connected across the track, a track relay at a distance from the source supplied with cur rent therefrom through the track rails, and.

Y a second track relay' connected in shunt to opposite short lengths ofthe-track circuit at a int intermediate the source and the first re ay, the contacts of'the. two relays being connected in different control circuits.

5.- In combination with an electric railway, a block signal system in which the track circuits are not separated from each other by insulated joints, comprising signals for the blocks, control circuits therefor, sourcesof alternating current connected across the railsat intervals, conductors cross-connect point from the source tosignal system coniprising signals for the blocks with control circuits therefor, a source of alternating current coning the smile at points between-said sources :and forming said sources and the nails closed :traok icircmts, 'tra ck relays .operatively .a'elatcd'tosaid track circuits near said conduotoraaiad sa'i trankmelay :cgnneoted shunt apontionof a snack circuit at "a point intermediate the "source and-the conductor and thawing :itstcontacts connected in a control circuitother than-that in which are connected the contacts of the relay near the conductor of said track circuit. 7

6. In combination with an electric railway, a'block signal system in which the track circuits are not separated by insulated joints comprising signals for the blocks, control circuits-therefor, sources of alternating current connected across the rails at intervals, conductors cross-connecting the rails at points between said sources and forming with said sources and the rails closed track circuits, track relays operatively related to said tracklicirc'uits nearsaid conductors, and atrack relay co 7 i portions of a'track'circuitat a point mterted in shunt to opposite mediate the source the-conductor andi having its contacts connected'in acontrol circuit other than {that in whichare connected the'contactsi ofjthe relay near the con- 1 "intervals, conductors cross-connecting the rails at pointsbctwecn said sources and form- .ing WltlVSBMI sources and the rails closed erefor, sources of alter;

. tracktcircuits,'-tracl: relays operatively rehaving a ener ed h the curre'nt flow pastjthat pomt in e tr circuit comsaid source and said conductor.

combination withan electric rail-I await said track circuits near said conduct'orsg .al track relaylocated at a point 'mterinediate a source and a conductor-tand- ,way, a block signal systemin which the track circuits are not separated by insulated joints,ficomprisi s1 Is for the-blocks,

control circuits t ere or, sources of alter intervals, conductors cross-connecting the" nating' current connected across the rails at rails at points between said sources and. formingwith said souroesand-the rails closed track circuits, track relays operatiyely related to said track circuits near said conductors, and struck relay located .at a point "intermediate a source and a conductor and having a winding energized by the current flow in both rails past that point in the track circuit comprising said sourceand said con.- uc

- ,9. In a block si a1 system comprising signals for the bloc 'with control circuits therefor, a sofiice of alternating ciii'i'eiit connected across the track; a track relay at a,v

distance from the source supplied with current therefrom through the track rails, and a. second track relay connected to the rails at a, point intermediate the source and the first. relay and supplied with current from the said source, the contacts of the two relays being connected in difl'erent control circuits. r

In witness whereof, I have hereunto set my hand this 17th day of March, 1909.

LAURENCE A. HAWKINS. Witnesses:

HELEN ORFORD, MARGARET E. WOOLLEY. 

